I got a trooper (dormant/friendly) as an actor of a cinematic part of my wad and want him to transform into a zombie (at a given time). Is there an ACS function to 'turn' one thing into another thing?
I dont want to do multiple teleports.. I want it to transform for real, just for the sake of the effect.
thanks in advance!!

You mostly just want an animation I suspect, so I'd first draw whatever frames you need. Maybe make a new monster called "transition" with decorate that just plays the morphing frames. thing_remove() the first thing, spawn() the transition thing, thing_remove() the transition and spawn the final thing. Is my guess.